Body support furniture currently in use falls broadly into two categories: elastic type, such as inner spring construction, and fluid type, such as waterbeds. In the elastic support type the pressure distribution provided is largely a function of the differences between the contour of the body surface in direct contact with the furniture surface and the unloaded contour thereof. In the case of a bed, the unloaded contour would normally be flat. Those portions of the body which project the most, in the heavier sections of the body, such as the pelvic or scapular sections, are reacted upon by the higher levels of the elastic support pressure distribution. The reactions of the elastic type support are by definition proportional to deflection. The support force distributions from such systems do not, in general, match the weight distribution of the supported body unless the body bends in ways to make its surface conform to the unloaded contour of the support surface. If the body does not conform in this fashion it must act like a structural beam providing a bridging action from one support point to another. To act as a rigid beam the required muscle tension leads to an internal source of discomfort in addition to the discomfort created by the concentration of support forces at discrete locations along the surface of the body. Another characteristic of elastic support systems is that in order to provide a smoother pressure distribution along the body surface a relatively soft support is required. A soft support usually sags excessively in the lumbar region and often results in internal discomfort.
Fluid support systems, such as waterbeds, on the other hand, overcome to a large degree the irregular nature of the support force distribution of elastic systems and provide support force distributions much less dependent on surface contour. Certain other disadvantages, however, are inherent in waterbeds, such as the relatively large mass and bulk of the devices, the need for heaters, and the wave motion.
Accordingly, it is an object of this invention to provide a support system for furniture, such as beds and chairs, which will readily adapt to the contours of different bodies and their aspects supported thereby.
Another object is to provide a support system which will readily conform to changes in contour of a body being supported by reason of shifts in body position.
A further object is to provide a support system for furniture by which bodies thereon are supported with a distribution of pressure that varies smoothly and is spread over a relatively large area of the body surface and minimizes the spread between the highest and lowest levels of the pressure distribution.
A still further object is to provide a support system for furniture by which bodies thereon are supported by a largely predetermined distribution of support pressures and in which little variation in local resultant support forces occurs even when the body contour changes.
Yet another object is to provide a support system for furniture which provides a support force distribution matched to the weight distribution of the supported body, independently of the body contour in contact with the support system.
Other objects are to provide a support system for furniture which permits the selection of any of a plurality of desired support system force distributions; to provide a support system that can have the comfortable feel of a soft mattress pad in contact with the body while effecting the kind of support needed for a natural body posture in order to prevent internal muscle tension; and to provide a support system whose support forces closely match the weight of each body section.